Sparse grass at winter closure delays turn-out

LEAVING too little grass when closing up grazing ground for winter can delay turnout by up to a month, according to a Milk Development Council-funded study.

Speaking at an MDC Focus Centre meeting at Harper Adams University College, Shrops, the colleges Russell Readman said a sward left at 6cm (2.4in) on Dec 1 had delayed turnout date in a study last year.

There was little difference between the other three treatments used; grazing to 6cm (2.4in) or 10cm (4in) on Oct 1 and grazing to 10cm (4in) on Dec 1. All produced similar amounts of dry matter in spring. There was no evidence of winter kill in the swards left longer, but it was a mild winter, he added.

"But there was no benefit in leaving extra grass on the sward grazed only to 10cm in Oct, indicating that you may as well use that grass in autumn. Grass growth rate was also higher in the 6cm sward, so that may have produced a higher quality sward.

"However, when keeping cows out into December and grass is grazed to 6cm there is a reduction in grass growth and here turnout would have been delayed by a month last year."

When extending the grazing season, therefore, the later cows graze the longer grass should be left for maximum spring growth. Alternatively, some paddocks can be grazed down to help achieve a grazing wedge for rotational grazing in spring, said Dr Readman.

It is commonly said that leaving newly grown grass over winter is beneficial. But comparing the growth of grass left to grow from October until December with grass grazed to 10cm in December shows there was no benefit from grazing tight and allowing fresh regrowth before winter, in this study.

The study will continue this year at Harper Adams, SACs Crichton Royal Farm, and at the Agricultural Research Institute of Northern Ireland, Hillsborough, Co Down.